Optimal control method for reactive voltage of wind power and photovoltaic power centralized grid connection

Abstract

The present invention has disclosed an optimal control method for reactive voltage of wind power and photovoltaic power centralized grid connection in the field of wind power and photovoltaic power grid connection control technology, comprising: setting actuating stations used to control single wind power plant/photovoltaic power plant, setting substations used to control actuating stations and set master station used to control all the substations; master station calculates setting voltage reference U ref of each substation; adopting 3σ method to process set voltage reference U ref to obtain set voltage reference interval; regulating high-side voltage of substation to make it fall in set voltage reference interval; if high-side voltage of substation does not fall in set voltage reference interval, then regulating the equipment in wind power plant/photovoltaic power plant via actuating station. The present invention guides the actual operations of electric power system.

The invention claimed is: 
     
       1. An optimal control method for centralized grid connection of wind power and photovoltaic power characterized in that the method comprises:
 step  1 : setting actuating stations to control a single wind power plant and a single photovoltaic power plant at a connection point of the wind power plant and the photovoltaic power plant, setting substations to control actuating stations at grid connection points of the wind power plant and the photovoltaic power plant and setting a master station to control all the substations; 
 step  2 : master station collecting electric power data of each wind power plant/photovoltaic power plant via the substations and the actuating stations and calculating a set voltage reference U ref  of each substation according to the collected data; 
 step  3 : processing set voltage reference U ref  by using three standard deviation method, then obtaining set voltage reference interval of [U ref-min ,U ref-max ]; 
 step  4 : regulating a high-side busbar voltage of the substation to make it fall in the set voltage reference interval of [U ref-min ,U ref-max ]; 
 step  5 : if the high-side busbar voltage of the substation does not fall in the set voltage reference interval of [U ref-min ,U ref-max ], regulating equipment of the wind power plant/photovoltaic power plant via the actuating station. 
 
     
     
       2. The optimal control method according to  claim 1  characterized in that the step  3  comprises:
 step  101 : setting the voltage reference U ref  as mathematical expectation μ, namely letting μ=U ref ; 
 step  102 : calculating reactive voltage control sensitivity S of the substation, computational formula of which being S=(J QV −J Qθ J Pθ   −1  J PV ), wherein, J Pθ , J PV , J Qθ  and J QV  refer to Jacobian matrix respectively; J Pθ  is the Jacobian matrix formed by listing the elements of ΔP/Δθ together; J PV  is the Jacobian matrix formed by listing the elements of ΔP/ΔV together; J Qθ  is the Jacobian matrix formed by listing the elements of ΔQ/Δθ together; J QV  is the Jacobian matrix formed by listing the elements of ΔQ/ΔV together; ΔP, ΔQ, Δθ and ΔV represent active micro-increment, reactive micro-increment, voltage phase-angle micro-increment and amplitude micro-increment of the substation respectively; 
 step  103 : determining minimum adjustable capacity Q min  of the equipment of each substation; 
 step  104 : calculating variance σ with formula σ=√{square root over (S −1 Q min )} and making [μ−3σ,μ+3σ] as the set voltage reference interval. 
 
     
     
       3. The optimal control method according to  claim 1  characterized in that the step  3  comprises:
 when the voltage needs to be reduced, decreasing input of capacitive compensation equipment and/or increasing input of inductive compensation equipment; 
 
       when voltage needs to be raised, increasing input of capacitive compensation equipment and/or decreasing input of inductive compensation equipment;
 wherein standard to judge the voltage is whether the voltage of the substations falls within the interval [μ−3σ,μ+3σ], if the voltage falls within the interval, no adjustment is needed; otherwise when the substations voltage is higher than μ+3σ, the voltage needs to be reduced, the substations voltage is lower than μ−3σ, the voltage needs to be raised. 
 
     
     
       4. The optimal control method according to  claim 2  characterized in that the step  3  comprises:
 when the voltage needs to be reduced, decreasing input of capacitive compensation equipment and/or increasing input of inductive compensation equipment; 
 
       when voltage needs to be raised, increasing input of capacitive compensation equipment and/or decreasing input of inductive compensation equipment;
 wherein standard to judge the voltage is whether the voltage of the substations falls within the interval [μ−3σ,μ+3σ], if the voltage falls within the interval, no adjustment is needed; otherwise when the substations voltage is higher than μ+3σ, the voltage needs to be reduced, the substations voltage is lower than μ−3σ, the voltage needs to be raised.